Temperature control system



I Aug 2l, 1934. n. s. TAYLOR 1,970,938 I TEMPERATURE CONTROL SYSTEMOfiginal Filed Jan.10, 1951 2 Sheets-Sheet '2 a 80a 57 a 6, 67 8/ 1 6O50 I 50 3/ g 9/ e5 82 e4 .5 82 84 a 46 he 7 #7 fok/vkys whereat theswitch is Patented Aug. 21, 1934 1,970,988 TEMPERATURE CONTROL SYSTEMDaniel G. Taylor, Minnea polls, Minn., assign or toMinneapolis-Honeywell Regulator Company,

Minneapolis,

Minn., a corporation of Delaware Original application January'1 0, 1931,Serial No. 507,863. Divided and this application April 11,

1932, Serial No. 604,491

24. Claims. (Cl- 23611) This invention relates generally to improve-'ments in temperature control apparatus, is particularly concerned with asystem of control for a hot air furnace, and is divisional of mycopending application for Temperature control apparatus, Serial Number507,863, filed January 10, 1931.

Features of the invention include: the direct adjustment of forcedcirculation-controlling means, coordinately withcombustio'n-rate-varying means, and/or in response to varying tem'-.

' perature of air delivered by the furnace; the concurrent control ofthe furnace draft and aircirculation-forcing means in response totempera: ture variation in the room; the direct adjustment of thethermostatically controlled circulation forcing means and/or directmechanical adjustment of that means; the adjustment concurrently withthe combustion-rate-varying means, or only in response to the varyingtemperature of air delivered by the furnace.

Objects, features and advantages of the invention will be set forth in'the description of the drawingsforming part of this application, and insaid drawings Figure 1 is a view illustrating the system, the partsbeing positioned as when the fan switch is mechanically locked .in openposition against thermostatic control, and'with the furnace draft, doorsclosed; M v

Figure 2 is a 'vertical longitudinal section through thethermostatically controlled switch device taken substantially on line 2.-2 of Figure 1, with the device conditioned-for control in response totemperature variations, to close the switch when furnace temperature issufficiently high;

Figure 3 is a front view with the parts positionally corresponding tothose of Figure 2; I

Figure 4 is a face view showing the hightemperature position of thedisks, with the switch closed; t

Figure 5 is a face view with the parts positioned in correspondence toFigure 1 with the switch mechanically locked in open position and withthe disk cams so positioned asto prevent switch movement by thermostaticaction;

Figure 6 is a fragmentary face view showing the positions of the disksas (lining a heat overrun, from the position shown in Figure 4; and

Figure 7 is a section on line 7-7 of Figure 2, illustrating theselectively adjustable thermostatic means for moving. the disks to aposition mechanically locked in means when the furnace heat.

position shown in the drawings.

- by gravity to the position ing means in response air of the furnacebefore delivery includes switch closed position, against change ofposition by thermostatic'action.

In the drawings, numeral 1 indicates a hot air furnace; numeral 2 theash pit draft door; and numeral 3 the cold air return pipe. A boosterfan for forcing circulation of air in the pipe 3 is indicated at 4.Numeral 5 indicates what is known, as a -program" motor, which controlsthe draft doors, and also effects an adjustment of a selectivelyadjustable thermostatically controlled means, to only permit closure ofa control switch for. the forced curculation producing is supplyingsuflicient This motor is electrically controlled by a room thermostat 22by means of suitable con-- vductors passing through conduit 21. Thiscir- .cuit is well known.

When the thermostat calls for heat, the motor is energized, the arms 7and 8 are rotated through an angle of 180 degrees and then the motorautomatically stops. On a call for less heat by the room thermosta themotor is again energized, the arms complete another 180. degrees ofrotation in the same direction and again assume the This type of motoris well known and,"therefore, its detailed construction is neitherillustrated nor described. The arm 8 is attached by a suitable flexibleelement 11- passing over pulleys 12, to a spring 13 which forms ayieldable connection between the chain and the thermostat adjustingelement 14. This element is weighted as at 15 and when released from itsposition shown in Figure Lgmoves shown in Figure 3. drawn to theposition against. the action of the The element 14 is, therefore, shownin Figure 1 weight 15.

The means for controlling theclrculatlon forcto the temperature of the55, and its electrical connections, carried in the conduit 16 andgenerally indicated at 17.-

The object is to prevent operation of the fan 4 when the furnace is notsupplying heat, and conversely to operate the fan as soon as the furnaceis producing the proper amount of heat. The arm 7 is connected with thedraft door 2 by a suitable chain 9 passing over rollers 10, and the arm8 is not only connected with the arm 14, but is connected by chain 11'with draft door 2". The arrangement issuch that when the door 2 isopened, door 2 is closed and vice ,versa; The draft doors may beconsidered broadly as any suitable means for varying rate of combustionin the furnace. The arms '7 and 8 are diamet:

I rically related. The result is that on rotation through an arc of 180degrees from the position shown in Figure 1, draft door 2 is opened,element 14 is released to be lowered by weight 15 to the position shownin Figure 3, and, as herein designed, the parts are thus conditioned forthermostatic switch closure on sufficient temperature rise at thefurnace, in this instance in the bonnet. With the parts positioned asshown in Figure 1, the switch is mechanically locked in open position,see Figure 5, against change to another control position by thermostaticaction.

The means for controlling the circulationforcing means in response tothe temperature of the air before delivery by the furnace is illustratedin detail in Figures 2 to 7. A, suitable housing is" indicated at 25 andis provided with a tubular bearing extension 26 suitably secured as at2'! to the housing. A tubular support is journaled in an outer reducedportion of the bearing extension, and has one end journaled in anopening 30 of the housing and extends into the housing. The opposite endextends beyond the bearing extension. J ournaled within the tubularsupport 29 is a rod 32 which projects therebeyond and into the housingand has its opposite end proiecting beyond the opposite end of thetubular support. A coiled thermostatic element 34 has one end connectedas at 36 to the element 29 and the opposite end connected at 3'! to therod. The thermostatic element is thus carried'by the support 29 and isadapted to rotate the rod in either direction conformably to temperaturechange. A dial disk 40 is suitably secured to the end of the rod 32within the housing and has graduations 41.

The instrument is properly calibrated by submitting the thermostat tosome predetermined temperature, say 100 degrees F. and then rotating thedisk 40 to register one'of its graduations with an imaginaryverticalline drawn through the axis of the rod and then fixing the disk to'theshaft for rotation therewith.

Rotatably arranged upon the rod are two cams 43-44. The cam 43'abuts theface of dial 40.

The cams have the form of stamped disks and are substantially identicalin configuration but are placed on the shaft in reverse position asshown. A spacing collar 45 separates the cams as best shown in Figure 2,and a clamping thumb nut 46 in threaded engagement with the rod isadapted to clamp the disksiafter adjustment) for motion with the rod.Each cam is provided with an arcuate slot 50 having a pointer'51extending inwardly from its outer periphery.

Through these slots, which are in register, the dial graduations can beobserved. Each slot is, of course, concentric with the axis of rotationof the rod. Each cam is also provided with a shoulder. The shoulder ofthe cam 43 is indicated by the numeral 52, and the shoulder of the cam44 is indicated by the numeral 53. These shoulders are faced in oppositedirections for a purpose presently to be described.

A mercury switch of the usual type is indicated at 55, and this switchis mounted Means pivoting the support to the housing is 111- dicated at57, and the axis of thismeans is parallel with the rod axis. The supportis disposed over and spaced from the periphery ofthe cams and the axisof the pivot support lies in a vertical line passing through the axis ofthe rod 32. The

support has extensions respectively indicated at.

60-6land respectively engageabl e by shoulders 52-53, and by theperipheral surfaces of cams on a support 56..

43-44. Ordinarily the shoulders are arranged in overlapping position asshown in Figure 3. The extensions are divergent toward the cams, and maybe said to Swaddle them. The tube support and extensions aresymmetrically balanced with reference to a vertical line drawn throughthe axes of rod and pivot means 57, so that overthe-center action bygravity may be obtained. A radial shoulder may be said to face towardthe inner surface of the corresponding extension, that is toward thosesurfaces of the extensions which are nearest one another. The shouldersmay be considered as tangent to a circle of less diameter than thediameter of a cam disk. The cam periphery between the shoulders issubstantially spiral, and it will be noted that the cam extensions andcam peripheries are so related that after engagement of either shoulderwith its extension and after the support is tipped there is no bindingaction between the parts. Thus, during. engagement of either shoulderwith its extension, the tube support is tilted to a gravity-maintainedposition, and thus whatever the degree and direction of motion of theshaft, no binding action between the extensions and cams can occur. Thecontact may be said to be gravity-maintained, only between the terminalof one of the extensions and the corresponding cam surface. Re-

ferring to Figure 6 (in which an over-run of the thermostat isrepresented) it is (seen that the terminal of the arm 61 rests upon therelative to the switch support and arms 60-61 thereof. It will be notedthat the thermostatic support 29 and thermostat can be bodily rotatedwith reference to these extensions without changing the position of thecams relative to one another.

One means for accomplishing this result (see Figure 'I) is by providingan arcuate slot 70 in the tubular bearing extension 26, and providing aplurality of angularly related radially disposed threaded openings, inthis instance two openings respectively designated '71-'15, in thetubular support 29. These openings extend into a plug '72 secured in therod support 29. The rod 14 has a weight 15 at the lower-end. and isselectively connectable with either of these openings. A larger numberof openings may be provided. When the rod is in the opening '75, thecams assume the position shown in Figure 3, and are conditioned topermit switch-closing operation as the result of thermostaticallyinitiated rod motion. When the rod is positioned to engage the upper endof the arcuate slot 70 as in Figure 5,

' no thermostatically initiated switch-closing operation can occur. Ifthe rod 14 is disconnected from the opening '15 and connected with theopeni'ng'71 and if, then, the rod is caused to assume the position shownin Figure '7, the cams will assume approximately the position shown inFigure 6, and the switch will be locked in closed position, so that nothermostatically initiated rod motion is great enough to cause shoulder53 to engage extension 61. Figure 6 may represent positionscorresponding either to a heat over-run from the position shown inFigure 4, or to a mechanical lock-out obtained by connecting the rod 14with the opening 71 and moving it to the position shown in Figure I.

The means 14 connected to the rod support, is adapted to rotate iteither to prevent or permit switch operation as the result ofthermostatically initiated rod motion, and means 11 connects 14 with 8for causing rotative adjustment of the rod to prevent a thermostaticallyinitiated switchclosing motion when the draft control is in draftclosedcondition, and vice versa. It is evident that v with the element 14 in araised position, the cams are so positioned (see Figure 5) thatthermostatic action upon these cams cannot close the switch. On theother hand, it is evident that when the element 8 rotates from itsposition in Figure 1, 14 is lowered, the rod support is swung andassumes the position shown in Figure 3, wherein the cams are sopositioned that the switch may be closed when the disks rotatesufliciently in counter-clockwise direction, under the heating action ofthe furnace.

3, the door 2 will be open because the arms 7 will Means has, therefore,herein been devised by which, through a mechanical connection,thermostatic switch operation is controlled by a,

damper-operating motor (or damper) so that the fan can be shut offirrespective of temperature of the furnace when the house issuflicien'tly warm,

and means has also been provided so thatin the summertime when thefurnace is not operating, the fan can be made to operate at all timesirrespective of temperature condition in either the furnace or in thehouse.

It is to be noted that the starting of the fan usually causes a drop offrom 15 to 30 in furnace temperature and for the proper operation thecam setting should be wide enough so that the first drop in temperaturewill not cause immediate stopping of the fan by tilting the mercurytube.

Otherwise the fan would be started and stopped rapidly If, while the'fan is operated, the room thermostat calls for less heat, the dampermotor closes, the damper lifts the lever 14 and therebychanges thecalibration of the thermostatic switch to such degree that the currentto the fan is,

immediately cut off. This is accomplished by turning the thermostat anddisk support through an angle of approximately 90.

Means is provided for limiting the rotative ad justment of the disks43-44 relative to one another to prevent such a degree of overlap of theshoulders 5253. as would cause them toassume an inoperative relationwith the extensions 60-61.

To this end, the dial 40 is provided with two stop pins substantiallydiametrically related and respectively indicated 81. These pins looselytraverse the slots 50 of both disks 43 and 44. The pin 81 and the end 82of the slot 50 of the disk 44 cooperate to limit adjusting motion of thedisk' 44 in counter-clockwise directio'n. Disk 43 is provided with astop pin '84 which is disposed immediately adjacent the end 85 of theslot 50'of that disk, which pin traverses the slot 50 of the disk 44.This pin 84 and-the end 86 of the slot 50 of the disk 44 cooperate tolimit counterclockwise motion of the disk 43, when the pin 81 is engagedwith the end 82 of that slot. Pin 80 and the-end 85 of slot 50 of disk43 cooperate to limit clockwise motion of the disk 43, and when 80 and85 are engaged the pin 84 limits clockwise motion However, it will benoted that. when the parts are positioned as shown in Figure ,slottherewith. It will, of course, be understood that these pins may bearranged diiferently in different installations, and are only for thepurpose of limiting disk rotation within the range of the particulardesign.

I claim as my invention:

1. In a control system fora hot air furnace, means for varying the rateof combustion in the furnace, means for forcing circulation .of airheated by the furnace, means controlled by the furnace temperature forcontrolling the circulation-forcing means. including means adjustable toeither permit or prevent operation of the circulation-forcing'means, andmeans by which said adjustablemeans is adjusted coordinately with thecombustion-rate-varying means and/or in response to varyingtemperatureof the air delivered by the furnace.

2. In a control system for a hot air furnace, a

room thermostat, means for varying the rate of combustion in the'fumace,means for forcing circulation of the air heated. by the furnace, meansfor controlling said circulation-forcing means in response to thetemperature of the air before delivery by the furnace, including aswitch, means adjustable respectively to permit 1 and preventthermostatic control of the switch, and means controlled by the roomthermostat for adjusting said adjustable means to permit thermostaticcontrol and concurrently operating said' combustion rate-varying meansto increase the combustion rate, and vice versa.

'3. In a control system for a hot air furnace, a

a and concurrently and correspondingly controlling said combustionrate-varying means conformably to temperature variations in the room.

4. A hot air furnace including, a heat delivery line, and draft controlmeans, a. fan adapted to increase circulation inthe heat delivery line,a circuit for said fan, means responsive to temperature at the furnaceand adapted to control a fan circuit including a switch, and meansmovable independently of the switch and adapted respectively tocondition the switch for thermostatic contrial and against thermostaticcontrol, and means for controlling the adjustment of said support, andconcurrently controlling the draft control means.

5. A hot air furnace including a heat delivery line and draft controlmeans, a fan adapted to increase the circulation in the heat deliveryline, a circuit for said fan, means responsive to temperature at thefurnace and adapted to control the fan circuit, including a switch andmeans adjustable to condition the switch for thermal control or tosecure it in either switch control position against thermal control, andmeans by which the space to be heated, means for varying the rate ofcombustion in the furnace. means for forcing circulation of air heatedby the furnace, means responsive to the temperature of furnace airbefore delivery, for controlling said circulation-forcing meansincluding a switch and a support, means by which the position of saidsupport can be selectively adjusted to condition it for thermostaticcontrol of said forced circulation-producing means or secure it ateither of two control positions respectively to prevent or permit suchthermostatic control, and means controlled by variations in thetemperature of the space for concurrently controlling saidsupport-adjusting means and said combustion rate-varying means.

'7. In a control system for a hot air furnace, means for varying therate of combustion in the furnace, means for forcing circulation of airheated by the furnace, means controlled by furnace temperature forcontrolling said circulationforcing means, including a switch and asupport, means by which the, position of said support can be selectivelyadjusted to respectively permit and prevent operation of the switch, andmeans for concurrently controlling said support-adjusting means and saidcombustion rate varying means.

8. A control system forja hot air furnace comprising a furnace, meansfor forcing circulation of air heated by the furnace, means forcontrolling the 'rate of combustion in the furnace, adjustable meansthermostatically controlled by fur.- nace temperature for controllingsaid circulationforcing means, and means for adjusting said adjustablemeans, and concurrently operating said combustion rate-controllingmeans.

9. In combination with a hot air furnace, means for forcing thecirculation of air heated by the furnace, thermally controlled meansresponsive to the temperature of furnace air before delivery and adaptedto control said circulation-forcing means, and adjustable respectivelyto respond or not respond thermostatically, means for controlling thecombustion rate of the furnace, and means by which said adjustable meansand combustion rate-controlling means are. cooperatively controlled inresponse to temperature changes at the delivery point of air heated bythe furnace.

10. In combination with a hot. air furnace, means for forcing thecirculation of air heated by the furnace, thermally controlled meansresponsive tothe temperature of furnace air. before delivery and adaptedto control said circulationforcing means, and adjustable respectively torespond, or not respond, thermostatically, means for controlling thecombustion rate of the furnace, means by which said adjustable means andcombustion rate-controlling means are cooperatively controlled, athermostat responsive to temperature changes at the delivery point ofair heated by the furnace, and means by which the thermostat controlsthe last mentioned means.

11 ,\-,In ,combination with a hot air furnace, mean'sfor forcing thecirculation of air heated by the furnace, and a switch for controllingsaid means, thermally controlled-means responsive to the temperature offurnace at before delivery and adjustable respectively to lock theswitchin either of its control positions, or to condition the switch forthermostatic control, means for controlling the combustion rate of thefurnace, means by which said adjustable means and combustionrate-controlling means are cooperatively con-' trolled, a thermostatresponsive to temperature changes at the delivery point of air heated bythe furnace, and means by which the thermostat controls the lastmentioned means.

12 In combination with a hot air furnace, means for forcing thecirculation of air in the furnace air delivery line, thermally controllemeans responsive to the temperature of furnace air before delivery andadapted to control said circulation-forcing means, means by which saidlast mentioned means can be adjusted respectively to respond or notrespond thermostatically, means for controlling combustion rate of thefurnace, and means by which said adjusting means is controlled inresponse to temperature changes at the delivery point of the forced air.

13. In a control system for a hot air furnace, means for varying therate of combustion in the furnace, means for forcing circulation of airheatedby the furnace including a switch, a rotatable support havingtherrnostatic means for rotating it in response to the temperature ofthe air before delivery by the furnace, said support and said switchhaving means cooperable to operate the switch as the result of rotationof the support, a rod detachably connected with the support for rotatingit and adapted to be selectively connected to the support in differentangulet relations thereto, and means by which said,

rod is alternately moved in opposite directions coordinately with saidcombustion-rate-varying means.

14. In combination a hot air furnace having draft control means, a fanfor increasing the hot air circulation in the hot air delivery line,thermostatically controlled means for controlling the draft controlmeans to open it on a call for heat and close it after the heat call issatisfied, a rotatable support, a rod journaled on the support, athermostatic element exposed to furnace temperature and movable withsaid support and rod, and adapted to reverselyrotate the rod conformablyto temperature changes, a switch, electrical connections between theswitch and the fan, means upon the rod for operating the switch to closeit when the'temperature rises and to open it when the. temperaturefalls, means connected to the support to obtain a rotative adjustmentthereof either to prevent or permit switching action as a result ofthermostatically initiated rod motion, and means for causing rotativeadjustment of the rod to prevent a thermostatically initiated switchclosing action, when the draft control means is in draft-closedcondition, and vice versa.

15. In a control system for a heating device for heating a circulatingfluid medium, in combination, means for varying the supply of heat tothe fluid medium, means for circulating the fluid medium,thermostatically controlled means responsive to the temperatureof thefluid medium for controlling saidcirculating means, thermostaticallycontrolled means responsive to a condition other than the circulatingfluid medium for controlling the heat supply varying means and.

means controlled by the heat supply varying means for conditioning saidthermostatically controlled means to operate the circulating means whenthe heat supply varying means is operating to supply more than a minimumamount of heat to the fluid medium and when the fluid medium is at orabove a predetermined temperature.

16. In a control system for a heating device for heating a circulatingfluid medium, in combination, means for varying the supply of heat tothe fluid medium, means for circulating the fluid medium,thermostatically controlled means responsive to' the temperature of thefluid medium for controlling said circulating means, thermostaticallycontrolled means responsive to a condition other than the circulatingmedium for controlling the heat supply varying means and meanscontrolled by the heat supply varying means for adjusting saidthermostatically controlled means to render the same operable to operatethe circulating means when the heat supply varyingmeans is supplyingmore than a minimum amount of heat to the fluid medium and the fluidmedium is at or above a predetermined temperature.

17. In a control system for a heating device for heating a circulatingfluid medium, in combination, means for varying the supply of heat tothe fluid medium, a thermostat in the space to be heated in control ofsaid heat supply varying means, means in control of the circulation ofthe fluid medium, thermostatically controlled means conditioned foroperation by said heat supply varying means when the same is operated bythe space temperature thermostat to supply more heat to the fluidmedium, and connections between the thermostatically controlled meansand circulation control means whereby the latter is operated by theformer when the former has been conditioned for operation and the fluidmedium is at or above a predetermined temperature.

18. In a control system for a heater for heat ing a fluid medium, incombination, means for varying the rate of combustion in the heater,circulating means for circulating the fluid medium, thermal meansresponsive to the temperature of the circulating medium, and meansmechanically controlled by the combustion rate-varying means and thermalmeans for operating the circulating means.

19. In a control system for a heater for heating a fluid medium. incombination, means for varying the rate of combustion in the heater,circulating means for circulating the fluid medium, thermal meansresponsive to the temperature of the circulating medium, meanscontrolled by the combustion rate-varying means and 1 thermal means foroperating the circulating means when the fluid medium is at or above apredetermined temperature and the combustion rate-varying means isoperating to increase combustion, and a thermostat responsive to thetemperature of the space to be heated in control of said combustionrate-varying means for operating the same to increase combustion whenthe space temperature falls below a predetermined minimum.

20. In a control system for a heater and a circulating fluid mediumheated thereby, in combination, means for varying the rate of combustionin the heater, an electrically operated circulator for circulating thefluid medium, a circuit for said electrically operated circulator,thermal means responsive to the temperature of the fluid medium, andswitching means mechanically controlled by the combustion rate-varyingmeans and said thermal means for completing the circuit for theelectrically operated circulator when the fluid medium is at or above apredetermined temperature and the combustion rate-varying means isoperating to increase combustion.

21. In a control system for a heater and a circulating fluid mediumheated thereby, in combination, means for varying the rate of combustionin the heater, an electrically operated circulator for circulating thefluid medium, a circuit for said electrically operated circulator,thermal means responsive to the temperature of the fluid medium,switching means controlled by the combus= tion rate varying means andsaid thermal means ture falls below a predetermined minimum.

22. In a control system for a heater and a circulating fluid mediumheated thereby, in combination, means for varying the rate of combustionin the heater, an electrically operated circulater for circulating thefluid medium, a switch in circuit with said electrically operatedcirculator, thermal means responsive to the temperature of the fluidmedium, and means controlled by the combustion rate-varying means andsaid thermal means for operating saidswitch to closed circuit positionwhen the combustion rate-varying means is operating to increasecombustion and the fluid medium is at or above a predeterminedtemperature.

23. In a control system for a heater and a' circulating fluid mediumheated thereby, in combination, means for varying the rate of combustionin the heater, an electrically operated circulator for circulating thefluid medium, a switch in circuit with said electrically operatedcirculator, thermal means responsive to the temperature of the fluidmedium, means controlled by the combustion rate-varying means and saidthermal means for operating said switch to closed circuit position whenthe combustion rate-varying means is operating to increase combustionand the fluid medium is at or above a predetermined temperature, and aspace temperature responsive thermostat in control of the combustionratevarying means. 1

24. In a control system for a heater for heating a circulating fluidmedium and provided with a draft damper, in combination, a roomthermostat, a damper motorcontrolled thereby, an electrically operatedcirculator for circulating the fluid medium, a themostatic switchresponsive to the temperature of the fluid medium, a circuit for theelectrically operated circulator including said switch, and connectionsbetween the heater draft damper, the damper motor and thermostaticswitch whereby the thermostatic switch conditioned to complete thecircuit to the electrically operated circulator when the fluid 13 mediumtemperature is at a predetermined point and the draft damper is open toincrease combustion in the heater.

DANIEL G. TAYLOR.

